In response to neighborhood anger at the slowing pace of Harvard University’s expansion in Allston, Mayor Thomas M. Menino is putting pressure on the university to get its construction act together.

Menino, whose administration initially downplayed Harvard’s decision to delay construction of its new $1 billion science complex in Allston, has fired off a letter to Harvard President Drew Faust, demanding meetings with the city and explanations about Harvard’s numerous vacant buildings in Allston.